(CNN) - This week, Barak Barfi, the spokesman for slain American journalist Steven Sotloff’s family, joined many Muslims in exposing the hypocrisy and hollowness of groups like ISIS.

He challenged ISIS leader Abu Bakr al-Baghdadi to a debate that pits Islam’s theology of life against ISIS’ cult of death.

In doing so, Barfi cited verses in the Quran that shun murder even a 6-year-old could understand: "Fight in the cause of God those who fight you and do not transgress, God loves not the aggressors" (2:190).

This verse is about self-defense. It allows one to protect civilians by fighting combatants who attack first. It forbids aggression, which is a grave sin in Islam.

By citing this verse, Barfi challenged all extremists to a debate that would expose their bankrupt cult of death for the forgery it is.

Barfi also talked about mercy in Islam. Mercy is an essential attribute for Muslims. God delivered Prophet Mohammed to humanity to make us more merciful to one another.

The CNN Belief Blog covers the faith angles of the day's biggest stories, from breaking news to politics to entertainment, fostering a global conversation about the role of religion and belief in readers' lives. It's edited by CNN's Daniel Burke with contributions from Eric Marrapodi and CNN's worldwide news gathering team.